While I agree readability is key, you may find people who disagree about what constitutes "readable". I think the Go community in particular may be partially inspired by the philosophy outlined under "Variable names" in Rob Pike's "Notes on Programming in C":

https://www.lysator.liu.se/c/pikestyle.html

Quoting:

"Ah, variable names. Length is not a virtue in a name; clarity of expression is. A global variable rarely used may deserve a long name, maxphysaddr say. An array index used on every line of a loop needn't be named any more elaborately than i. Saying index or elementnumber is more to type (or calls upon your text editor) and obscures the details of the computation. When the variable names are huge, it's harder to see what's going on."

I don't agree with everything written therein, and it was written circa 1989. But in practice single letter variable names are used diligently and frequently in Go, they're convenient and don't break readability if you understand the (simple) convention.